Power-driven lawn mower



April 22, 1930.

A. E. JERRAM POWER DRIVEN LAWN MOWER Original Filed March 23, 1927. 4Sheets-Sheet 1 April 22, 1930.

A. E. JERRAM POWER DRIVEN LAWN MOWER Original Flled March 23. 1927 4Sheets-$heet 2 QA Z1 firm/m I 1% are/hw iibrnqyst' I [nugnlbr April 22,1930. A. E. JERRAM 1,755,958

POWER DRIVEN LAWN MOWER Original Filed March 23, 1927 4 Sheets-Sheet 5April 22, 1930. A. E. JERRAM POWER DRIVEN LAWN MOWER Original FiledMarch 25, 1927 4 Sheets-Sheet 4 Patented Apr. 22, 1930 ARTHUR ERNESTJERRAM, OF OADBY, ENGLAND POWER-DRIVEN LAWN MOWER Original application1, power-unit, a cutter, a driving roller, and

transmission mechanisms between the powerunit, the cutter .and theroller. Heretofore such machines as have been manufactured compriseaggregations :of a lawn-mower and a petrol motor designed forcotheruses, with the result that the transmission mechanism @has :beeninefficient and indirect, and the structure weak, top-heavy,:and unduly.cum- 'bersome, the machines requiring considerable care and attentionto keep them up to their work. As such machines .are frequently workedunder very'severe and varying conditions exposed to the weather and dirtand .a-reused' by persons, such as gardeners, who

se are not skilled mechanics it is very important that each of thesemechanisms, and particularly the power-unit, shall be well designed andskilfully arranged in conjunction with the rest inorder :to contributeto the satisas factory Working of the machine as a whole with a minimumofattention.

This inventionhas for 'itsfmain object to provide an improved powerunit-driven lawnmower that fulfils the above-mentioned con- 1 u ditions,and from which :the power-unit can be readily removedand replaced byunskilled labour in caseof need by loosening or securing only a minimumof attachment devices. Another object is to provide an improvedarrangement of water cooling .of such a reada) are obviated.

ri-ccordingto an important feature of the invention, there is providedin a power-unit- I driven lawn-mower the combination of'(a) awithdrawable power unit having quick release and clamping devices, (1))a fixed-centre driven shaft coaxial with the driving shaft (e. g.crankshaft) of the power-unit, guiding surfaces adapted to control themotion of withdrawal or replacement of the powereunit in a predetermineddirection, and

filed March 23, 1927,-Scria1:No. 177,791, and. in Great Britain April 1,1926. Divided and this application filed January 20, 1828. Serial No.248,196.

(d) a driving connection between said driving shaft and said drivenshaft that is separable by the said controlled motion of withdrawal ofthe power-unit, with or without (6) an exhaust connection soarranged asto be disconnected and connected by the aforesaid controlled motion,whereby the powerunit can be readily removed from the machine as aseparate unit by loosening the clamping devices, so that in the event ofbreak-down or failure of the 'powereunit it can be readily removed fromthe machine and a spare unit-can bereadily substituted therefor andfixed in its operative position on the mower Without per orming anyoperations requiring skilful manipulation.

'T he term fixed-centre used herein in relation to the driven shaft isintended to mean that the axis of rotation of the driven shaft is fixedin relation to the frame of the mower.

Conveniently, the clamping devices secure the crank-case of thepower-unit to the machine at only three points.

Preferably, the said guiding surfaces cooperate with guidingdevices inthe form of two slide-bars constituting cross-members of the frame ofthe mower, with which slidebars the power-unit may be supported atthreepoints, at which points readily releasable clampingidevices may engagethe slide-bars.

According to another important feature of the invention, there isprovided a powerunit-driven lawn-mower asset forth in the precedingparagraphs, wherein a power-unit in the form of a water-cooledinternal-combustion engine disposed in a slanting position has awater-supply tank of the hopper type that is formed or provided directlyon the detachable or other head of the engine and is open above to theatmosphere, which lawnmover is characterized in that the supply tank,for example a hemisphericaltank, preferably situated in view of theoperator of the mower when in use, opens into the upper portion of thebody of a water-jacket which is, for the purpose described hereinafter,in the form of an annular chamber at the cylinder head and surroundsonly a short length of the cylinder at the end adjacent the head.

Other features of thei'nvention will be described hereinafter andpointed out in the ap ended claims.

' gneembodiment of the invention is diagrammatically illustrated by wayof example in the accompanying drawings. In said drawings- Figure 1 is aperspective view of a complete power-driven lawn-mower provided with apower-unit according to the invention;

Figures 2 and 2 -are a plan thereof, with some parts removed and othersbroken away and partly in-section, and

Figure 3 is a section taken on the line 3-3 in Figure 2 showing thepower-unit and its fastening clips in side elevation.

Figure 4=is a horizontal section taken through the lower 'part'of theengine and through its supporting arms.

The figures are drawn to different scales, but like reference numeralsdesignate like parts throughout the severalviews- Referring to thedrawings, the powerdriven lawn-mower (Figure 1) has a'frame designatedgenerally by the numeral 10, comprising two side members 11, 12connected together by threemain cross members 13, 14,

in the formof stretcher rods arranged one, 13, at the front, a second,14, at the rear, and a third, 15, near the middle of the side 7 members11, 12; the second and third stretcher rods 14, 15 are substantiallyinthe same general longitudinal plane at the top of the side members 11,12. Other cross members in the formof distance rods may extendbetweenthe side members below the middle stretcher rod 15.

A rotary cylindric cutter has its shaft 21 journalled in ball-bearingsat 22 and 23 in the side members between the stretcher rods 13 and 15soas to be readily detachable in any convenient manner, but preferablyas described in my prior Patent No. 1,486,758. A driving or back rollerdesignated generally by the reference numeral 24 is journalled in theside members between the stretcher rods 14 and 15, and a front rollermade in sections, designated generally-:by the numeral 27, is

' journalled in the side members between the ing the cutter 20 and backroller 24 is detachably supported on the back and middle stretcher rods14, 15 by readily detachable fastening devices, in such a manner that itcan be readily removed m case of need. "For this purpose the crank-caseis formed or'provided' withtwo arms 31, 32 respectively extending foreand aft of the machine The rear arm .32 terminates in a clip that isdesignated generally and comprises a fixed jaw 33 and a movable aw 34,which jaws are of arcuateicrosssection and embrace the back stretcherrod 34, the jaw 331is' longer than the jaw 34 and makes contact only atits ends with the rod 14; the movable jaw 34 which is pivoted to thefixed jaw 33 can be closed on the stretcher rod by a single bolt 36 thatis pivoted on the fixed jaw 33 and extends through a hole in the movablejaw 34. The front arm 31 of the crank-case is detachably secured to themiddle stretcher rod 15 by a like clip 37 except that its fixed jaw 38having a'bolt39 is much shorter than the jaw 33 of, the clip 35 andcontacts with its stretcher rod 15 along the entire lengthof the clip.Guiding surfaces for controlling theniotion of withdrawal andreplacement of the engine are constituted by the inner faces of thefixed jaws aforesaid and by the'peripheriesof the rods 14 and 15 whichconstitute guiding devices. The motor'is thus supported'on the frameatthree situations lying at the angles of a triangle, so that even if thestretcher rods afiording two points of support may engage the rod '15and the clip 37 may engage the rod 14,,but the arrangementillustrated isthat preferred. v 1 I The preferred construction of power-unit, as shownin Figures l, 2fand 3, is a watercooled internal-combustion engine 30wherein a relatively small water-supply tank 40 shaped like a circularbowl is formed'or provided directly on the water-jacket 41 forming'partof the head of the engine, and is open above to the atmosphere and ispreferably situated in view of the operator of the mower when themachine is in use. The employment of a .radiator is thus obviated; thewater simply boils away and can be readily replenished when needed,because a lawnmower when iniuse isalways not far from 'a water supply,and the water'tank can be readily seen by the operator, it beingpreferthis way av satisfactory engine is obtained without any materialaddition to the weight of the mower, and furthermore a readilydetachable motor can be used without having to break complicated waterjoints .or the like such as are likely to be beyond the capacity of theordinary gardener to attend to.

The engine 30 cooled as aforesaid is disposed in a slanting position andthe body of the water-jacket 41 is,for the purpose describedhereinafter, in the form of an annular chamber at the cylinder head andsurrounds only a short length of the cylinder 42 at the endadjacent thehead, and the supply tank 40 opens into theupper portion of the saidannular chamber. The purpose of using; an annular chamber is to'leavethe centre of the cylinder head, which may. be afdetachable and may beintegral Withthe body :41 .of the jacket.

An impeller 43, for example a radial :flow :impellen'ispreferablyarranged to bedriven zby'the engine crankeshaft 44 forproducing a ,blast of air and means are :provided for directing .theblast against that portion .ofzthe body LOftl1Q cylinder 42 notsurrounded :by

the :water jacket 41. As illustrated, this impeller 43 is inthe form.ofa fly-Wheel mounted ,onzthe crankshaft and has cast in it radialpassages that'openat-one endzthroughzthc pe :riphery and at the otherend'through aside face of the flywheel, and the blast-directing am'eansis'in theform ofa casing 45 surroundthe fly-Wheel, which casing has anaxial inlet at i46and anioutlet at 47 so arranged that .a current of airis induced by the impeller to flow past the crank case for cooling thelatfer. When 'the engine cylinder is partly Water cooled and partly aircooled as described above, thebody 'ofthe cylinder below the :waterjacket is preferably provided with :the usual coolingfins 481011 towhich the'blast is directed. The casing :45 surrounding {the impeller is:secured as'loy bolts in any conyenientmannerzto the .crankcase 49.

Any convenient construction of driving gear may he :providedr-for'operatively con- ;nectingthe motor SO-svithatherotarycutterQO and thedriving roller 24. A preferred con- 'Z-StIUCtlQII is that described andclaimed in m-y coepending "patent application :Serial No.

177 ,7 91, from which the present application hasbeen dividedout.Thisconstruction comprises a :main driving shaft '51 arranged to drivethe cutterand back roller at different speeds. "This driving shaftol'is-the fixedcentre driven shaft referred to above; it lies parallelwith the said stretcher rods :13, :14, 715 andis engaged directly :by acoupling '52, 15-3 with the motor crank-shaft 44"which is also :parallel with the stretcher rods. This coupling '52, 53 may ;-be a slipcoupling of any convenient construction that enables the 7 two shafts44, :51 to :be disengaged and engaged by a simple movement of the motorin a .directionsparallelewith the stretcher, rods or in adirectionratright-angles thereto. As

' "illustrated'the:slip couplingtakesrtheform of a: selfealign-ingcouplingv of the Oldham type,

whereoflone element 5'3;isformed onan impeller 4'3 carried'byithecrank-shaftandthe other element "52 is "fast on the adjacent .end

of .zthe shaft :51.

The dri-vingcgear aforesaid comprises powver-tranemission meansdesignated generally lry-thenumeralz55 (EignrexQ) connectirng'the mainshaft 51 With the rotary cutter 120, and

tation is fixed in relation to the frameofthe mower.

An engine exhaust silencer 160 extends across the machine and has anelbow 164 at its centre with a slip connectionat 161 (Figures 2 and 3)with the exhaust pipe ofthe engine which is arranged in the directionofWithdrawal of the power-unit and parallel to the crank-shaft. Apetrol-tank 162 mounted on the handles 98 is connected to the carburetor165 so as to be readily disconnected therefrom. For starting the onginea handle maybe applied to what is .virtually the free end of the shaft51 having a notch 163 for engagement by it.

It will be appreciated that the invention provides a power-drivenlawn-mower suitable to be put in the hands of an unskilled operator. Theengine can be readily removed andreplaced on the frame by any personwithout the exercise of any mechanical skill, and owing to the Watercooling being arranged as described no difficulty Whatever isexperienced in connection with a radiator such as is used in motor-carpractice.

Various defects, such as high centre of gravity, considerable additionof weight'on the mower and increase in cost of manufacture andmaintenance, due to the use of a Water-cooled motor having a radiatorarranged as is usual in motor-car practice are avoided by the improvedvconstruction, in which various modifications maybe made Withoutdeparting from the scope ofthe invention as defined in the claims. lVithregard to Figure 4, it will be noted that this is a horizontal sectiontaken through the lower'part of the invention and through its supportingarms 31, 32, each having a clip. The fixed part 33 of the rear clip isshown broken away to indicate that the head 33 makescontact only at itsends withthe rod 14, and thus provides "two points of support spacedapart.

I claim:

1. Ina power-unit driven lawn-mower, the combination of a frame, arotary cutter journalled therein, anpower unit that has a drivrotarycutter, quick-releaseclamping means for securing the power-unit on theframe, gu de means :for controlling the motion of Withdrawal andreplacement .ofethe powerunit out of and into its driving-position onthe frame in a direction parallel with said driven shaft, and a readilyseparable driving connection that operatively connects said driving anddriven shafts in a line and is separable by the controlled motion ofwithdrawal of the power-unit.

2. In a power-un'it driven lawn-mower, the

V combination of a frame, a rotary cutter 'jour- 1 into itsdrivingposition of the frame, a reada nalled therein, a power-unit that has adrivlng shaft and is withdrawably mounted on the frame, transmissionmeans comprising a fixed-centre driven shaft for driving the rotarycutter, quick-release clamping means for securing the power-unit on theframe,

guide means for "controlling the,v motion of Withdrawal and, replacementof the powerumt m a predetermined directlon out of and ily separabledriving connection that operatively-connects said driving and drivenshafts,

an-exhaus't silencer on the frame, a readily separable exhaustconnection between the power-unit and the silencer, which driving andexhaustconnections are separable substantially simultaneously by thecontrolled motion of withdrawal of the power-Unit,

3. In a power-unit-driven lawn-mower, the

combination of a frame, a rotary cutter journalled therein, a power-unitthat has a driving shaft and is withdrawably mounted'on the frame atthree situations arranged at the angles of a triangle, transmissionmeans comprising a fixed-centre driven shaft for driving the rotarycutter, quick-release clamping means for securing the power-unit on theframe at said three situations, guide means for controlling the motionof withdrawal and replacement of the power-unit in, a predetermineddirection out of and into its driving position on the frame, and areadily separable driving connection that operatively connects saiddriving and'driven shafts and is separable by the controlled motion ofwithdrawal of the power-unit. 1 7

4:. In a power-unitdriven lawn-mower, the combination of a frame, arotary cutter journalled therein, a power-unit that has a crankshaft andis withdrawably mounted on the frame, transmission means comprising a Ifixed-centre driven shaft for driving the rotary cutter, quick-releaseclamping means for securing the power-unit on the'frame, guide means forcontrolling the motion of withdrawal and replacement of the powerunitout of and into its driving position of the frame in the direction oflength of said driven shaft, a readily separable driving connection inthe form of a self-aligning coupling that operatively connects saidcrankshaft end-to-end in a line and driven shaft and is separable by thecontrolled motion of withdrawal of the power-unit.

5. Ina power-unit-driven lawn-mower, the

combination of a frame, a rotary cutter journalled therein, a power-unitthathas a drivrotary cutter, brackets on the power-unit extendingtransverselyiof the driving shaft, quick-release clamping means on saidbrackets for securing the power-unit on the frame, guide meanscomprising two slidebars constituting cross members of the frame forcontrolling the motion of withdrawal and replacement of the power-unitin a predetermined direction out of and into its driving position on theframe, and a readily separable driving connection that operativelyconnects said driving and driven shafts and is separable by thecontrolledmotion of withdrawal of the powerunit, which clamping meanscomprises at least two clamping devices each in the form of a clipcomprising two jaws, whereof one is'on a said bracket on the power-unitand the second is movable thereon, and a nut-equipped bolt for holdingthe jaws closed on a saidcross bar of the frame.

6. In a power-unit-driven lawn-mower, the combination of a framecomprising two slidebars constituting cross members, a rotary cutterjournalled in said frame, a power-unit having a driving shaft parallelwith said slide-bars, transmission means comprising a driven shaftparallel with said driving shaft for driving the rotary cutter,quick-release clamping means in the form of clips for securing thepower-unit on said slide-bars, which slide-bars and the clipsco-operating therewith constitute guide means for controlling the motionof withdrawal. and replacement of the power-unit in a predetermineddirection out of and into its driving position on the frame, and areadily separable driving connection in the form of a selfaligningcoupling that operatively connects the said driving sh aft with saiddriven shaft and isseparable' by the aforesaid controlled motion ofwithdrawal of the power-unit.

7. In a power-unit-driven lawn mower, the

combination of a frame, a rotary cutter journalled therein, aninternal-combustion engine withdrawably mounted in a slanting positionon said frame, whic h engine has a water jacketin the form of an annularchamber at the cylinder head surrounding only a short length of thecylinder, and a water-supply tank of the hopper type that is carried bythe cylinder head andis openoabove to atmosphere and opens belowinto theupper portion of the body of the said water-jacket, transmission meanscomprising a driven shaft that is co-axial with the engine crankshaftand is to be driven thereby and is arranged todrive the rotary cutter,quick-release clamping devices for securing said engine on the frame,guiding surfaces for controlling the motion of withdrawal of the englneout of its driving position on the frame in the direction of length ofsaid driven shaft, and a readily separable coupling that operativelyconnects said crankshaft and driven shaft end-to-end in a line and isseparable by the controlled motion of withdrawal of the engine.

8. In a power-unit-driven lawn-mower, the combination of a frame, arotary cutter journalled therein, an internal-combustion enginewithdrawably mounted in a slanting position on said frame, which enginehas a water-j acket in the form of an annular chamber at the cylinderhead surrounding only a short length of the cylinder, and a water supplytank of the hopper type that is carried by the cylinder head and is openaboveto atmosphere and opens below into the upper portion of the body ofsaid water-jacket, a radial-fiow impeller constituted by a flywheel onthe engine crankshaft for producing a blast of air, means for directingthe blast against that portion of the body of the en ine cylinder notsurrounded by the water-j ac Iet, transmission means comprising a drivenshaft that is co-axial with the engine crankshaft and is to be driventhereby and is arranged to drive the rotary cutter, quickreleaseclamping means for securing said engine on the frame, guiding surfacesfor controlling the motion of withdrawal of the engine out of itsdriving position on the frame in the direction of length of said drivenshaft, and a readily separable coupling that operatively connects saidcrankshaft and driven shaft end-to-end in a line and is separable by theaforesaid controlled motion of withdrawal of the engine.

9. A combination of parts as set forth in claim 8, whereintheblast-directing means is in the form of a casing surrounding theimpeller, which casing has an inlet so arranged that a current of air isinduced by the impeller to flow past the engine crank-case for coolingthe latter. e

In testimony whereof I affix my signature.

ARTHUR ERNEST JERRAM.

